1. Field of Invention
This invention relates to structural thermoplastic foam, and more particularly relates to the use of polytetrafluroethylene resin as a nucleating agent for foamable thermoplastic resins, injection molding foam processes using the same, and thermoplastic resin compositions useful in the process.
2. Description of the Related Art
The production of thermoplastic structural aromatic polycarbonate foam articles by injection molding processes using either an inert gas such as nitrogen, a chemical blowing agent, or mixtures thereof, are well known in the art. Such processes typically use a thermoplastic resin which contains an amount of a nucleating agent which is added for the purpose of assisting in the formation of cell structures during the foaming process. The use of some nucleating agents such as clay have, however, in some circumstances can show an inability to uniformly expand the thermoplastic resins resulting in non-uniform cell structures and higher density foams than are desired.
Accordingly, there is a need for a nucleating agent which will enhance the uniformity of the cell structures formed upon expansion of the resin.